High-temperature superconducting thin-film strip conductors (HTSL-CC), also called coated conductors, are typically produced starting from a textured metal substrate formed from a face-centered cubic crystallizing metal (e.g., nickel, copper, gold). Nickel is especially suitable, in particular nickel having a few at % tungsten. The textured metal substrate is coated with a buffer layer, which transfers the texture of the metal substrate to a superconducting layer generated subsequently on the buffer layer. The buffer layer may be formed from materials having a low lattice mismatch to both the metal substrate and the high-temperature superconducting thin-film to be crystallized. Exemplary materials include materials that grow rotated by 45° on the metal substrate (e.g., lanthanum zirconate) and materials having fluoride or pyrochloride structure, as well as materials that grow unrotated and possess a perovskite structure (e.g., strontium titanate and calcium titanate) or a spinel structure (e.g., strontium ruthenate and neodymium nickelate).
Due to contaminants within the metal substrate, a chalcogenide superstructure (such as a sulfur superstructure) normally forms on the metal substrate. This superstructure encourages the epitactic growth of buffer layers deposited via physical methods (e.g., vapor deposition of the metal substrate in high vacuum). Therefore, it is desirable to reproducibly generate a uniform superstructure having a high degree of coverage. Unfortunately, the physical deposition of the buffer layer is a costly; consequently, it is not suitable for the production of an HTSL-CC, or even its carrier (metal) substrate.
An HTSL-CC may also be produced utilizing chemical coating methods (e.g., chemical solution deposition (CSD) and metal organic deposition (MOD)), which tend to be more cost effective. Results comparable to those achieved via physical methods, however, have not been achieved in materials that do not grow rotated by 45° (like lanthanum zirconate), or that are unrotated (e.g., strontium titanate, etc). Even if a metal substrate possessing a low surface roughness is used, the resulting structure includes strontium titanate layers are untextured or only weakly textured.
Thus, it would be desirable to provide an HTSL-CC formed via chemical coating methods that use materials that grow unrotated on the substrate, as well as to provide a highly-textured buffer layer and/or superconducting layer.